1. Field of the Invention
The present invention relates to a multi operating system, and more particularly, to an operating system switching method in a computer system having a multi operating system mounted thereon.
2. Description of the Related Art
Although a single operating system was installed in one computer system in the past, the development of a computer technology has enabled two or more operating systems to be installed on a computer system. An operating system configuration having two or more operating systems installed therein is referred to as a multi operating system.
Thus, a user has become able to perform a desired computing task in an appropriate operating system once a desired multi operating system configuration is constructed. During a computing task, if it is required that a different computing task be performed, a computer system must be switched from one operating system to another operating system. Thus, the computer system having a multi operating system typically provides an operating system switching function.
FIG. 1 is a flowchart illustrating a conventional operating system switching method. For the sake of convenient explanation, an operating system switching method in a computer system having Windows® and Linux® operating systems installed therein is illustrated in FIG. 1.
In step S100, it is assumed that the Windows® operating system is booted and is operating normally. In this case, in steps S110 and S120, when a user wants to switch the Windows® operating system to the Linux® operating system using a predetermined short key, the Windows® operating system switches a power management state of the computer system to a soft off state S5, which is described in more detail with respect to FIG. 2. In other words, the computer system uses a power management function so as to switch the operating system.
When switching a conventional operating system, a power management state is turned to a power management state corresponding to the S5 state 240 (FIG. 2) in step S120, so that the Windows® operating system is terminated. When power is turned on in step S130, bios booting starts in step S140. In this case, the power may be turned on through a user's power inputting button or automatically by the computer system. While the bios booting is performed, the user is asked which operating system the computer system is to be booted by in step S150. The user selects the Linux® operating system and then the computer system is booted by the Linux® operation system in step S160. Here, of course, if the user selects the Windows® operating system, the computer system will be booted by the Windows® operating system S100.
For a better understanding of a conventional operating system switching method, a power management function of the computer system will now be described briefly.
The power management system of the computer system has been advanced from an initially simple function to an enhanced function. Recently, advanced configurations and power interface (ACPI) specification have been proposed by Intel Corporation, Microsoft Corporation, and Toshiba Corporation. According to the ACPI specification, power management is not performed by BIOS (Basic Input/Output System) but is performed by an operating system. The detailed contents of the ACPI specifications are disclosed in “Advanced Configuration and Power Interface Specification Revision 1.0.”
FIG. 2 is a state diagram illustrating various states of a computer system according to the ACPI specification and transition of each state.
As shown in FIG. 2, the overall states of the computer system are five; a legacy state 210, a G0 state 220, a G1 state 230, a G2 state 240, and a G3 state 250.
In the legacy state 210, an ACPI function is disabled and power management is not performed. In the G0 state 220, the computer system normally works. In the G1 state 230, that is, a sleeping state, power consumption is gradually reduced. In the G2 state 240, that is, a soft off state, only a minimum of power is consumed to sense soft switching (switching of the computer system for power on/off). In the G3 state 250, that is, a mechanical off state, power supply is cut off.
In the state where the ACPI function is enabled and power is supplied, the computer system has six-stage sleeping states S0 to S5. An S0 state corresponds to the G0 state 220, states S1 to S4 232, 234, 236, and 238 (hereinafter, referred to as low-power sleeping states) correspond to the G1 state 230. An S5 state corresponds to the G2 state 240. In the low-power sleeping states 232, 234, 236, and 238, power consumption is gradually reduced according to an operating state of the computer system. In this state, the S1 state 232 is a low-power sleeping state in which all states of the computer system are stored, and the S2 state 234 is a low-power sleeping state similar to the S1 state 232 but a CPU cache and a system cache are not stored in the S2 state 234. The S3 state 236 is a low-power sleeping state similar to the S1 state 232 but information on hardware except for memory information is lost. In the S4 state 238, that is, a low-power sleeping state, the hardware stops operating. In the S4 state 238, power is almost cut off, and thus, it takes time to reuse the S4 state 238. However, the environment of the previously operated operating system, such as memory information, information on a variety of applications, or data information, is stored in a hard disc, which is referred to as image backup.
As shown in FIGS. 1 and 2, in the conventional operating system switching method, after the current operating system is completely terminated, bios booting is performed and booting by an operating system to be switched is then performed. When necessary, when or after bios booting, a process of asking the user to select an operating system may be performed.
In other words, in the course of terminating the current operating system, the overall time required for switching the operating system is prolonged and an unnecessary user's operation, such as user's selection of an operating system, is needed. These problems should be solved for a multi operating system that requires faster booting.
In addition, in switching the current operating system to an operating system dedicated to a specific purpose, the other processes or hardware that have not been used for the specific purpose may also be operated, which results in unnecessary consumption of system resource or power. Thus, in order to save system resource and power, what is needed is to operate only the processes or hardware needed for implementing the specific purpose.